One type of oilfield perforator that is in common use comprises an elongated tubular perforating gun having a plurality of laterally directed explosive shaped charges or shaped charges mounted at longitudinal spaced intervals on a carrier that is contained within the perforating gun body. The carrier positions the explosive charges within the gun body so that outlets of the shaped charges are directed laterally of the gun body. The gun body is a cylindrical member designed to withstand the significant explosive forces produced by the detonation of the explosive shaped charges and permit energy of the shaped charges to leave the gun body at selected locations.
In using this type of perforating equipment several common and well recognized problems appear. When the perforating gun is detonated the individual explosive charges are exploded and due to their design a significant thrust of their individual explosions passes through the associated ports in the gun body. However, a significant portion of this explosive force remains within the perforating gun body. If this force is excessively large it can cause excessive swelling, fracturing and/or severing of the gun body into two or more pieces. This is undesirable because fragments of the gun body and perforating equipment must be separately extracted from the well that has been perforated and this can be exceedingly difficult and time consuming. If this contained explosive force is less substantial it can cause some radial swelling of the perforating gun body. This swelling can be tolerated within limits in view of removing the perforating gun body from the well after the perforating operation.
Overcoming the two above described well known problems associated with oilfield perforating often involves a compromise in the gun body design and the strength of the explosive charge used. This compromise is one which will provide a maximum penetration of the perforation into the earth's formation which requires a greater effectiveness of the explosive while at the same time keeping the explosives charge small enough so that the gun body is not excessively swollen or fractured upon detonation of the explosives.